Chlorophyll b Interference in the Fluorometric Determination of Chlorophyll a and 'Phaeo-Pigments'

A quantitative estimate was made of the interference by chlorophyll b in the fluorometric determination of chlorophyll a using an Aminco-Bowman spectrofluorometer. The undegraded (or 'living') chlorophyll a concentration was underestimated by an amount equal to the concentration of chlorophyll b present. The value for chlorophyll a uncorrected for phaeophytin was increased by 30% of the chlorophyll b concentration. The acetone to water ratio was found to affect the acidification factor only at aqueous acetone concentrations above 90%. The need for standardization of solvent and wavelengths is discussed, and the implications of chlorophyll b occurring in marine samples are considered.